Electrical heating unit



F. KU HN AND J. A; HAND.

ELECTRICAL HEATING UNIT. APPLICATION FILED JAN-.25, I919.

Pdtented Apt 26,1921;

anyone/11.5

UNITED STATES PATENT OFFICE;

FRANK KUHN AND JAY A. HAND, OF DETROIT, MICHIGAN, ASSIGNORS TO AMERICANELECTRICAL HEATER COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OFMICHIGAN.

ELECTRICAL HEATING UNIT.

Specification of Letters Patent. Patented A131, 26, 1921.

Application filed January 25, 1919. Serial No. 273,080.

T 0 all to 710m it may concern:

Be it known that we, FRANK KUHN and JAY A. HAND, both citizens of theUnited States of America, residing at Detroit, in the county of IVayneand State of Michigan, have invented certain new and useful Improvementsin Electrical Heating Units, of which the following is a specification,reference being had therein to the accompanying drawings.

The invention relates to armored electrical heating units designed forimmersion in liquids, and the invention consists in the construction ashereinafter set forth.

In the drawings:

Figure l is a perspective view of the unit;

Fig. 2 is a side elevation thereof;

Fig. 3 is a longitudinal section;

Fig. 4 is a perspective View of the resistor element detached from'itsarmor;

Fig. 5 is a section similar to Fig. 3 but in the plane of one of theterminals.

For use in water heaters and for similar purposes it is frequentlydesirable to provide for the insertion of the heating unit through thewall of the container. This necessitates a waterproof armor for theresistor and also means for forming a watertight joint with the casing.This we have accomplished by the combination of a closure plug or capand av projecting seamless casing integrated therewith, having its outerend in open communication with a recess in the plug. Within this recessan insulator conductor block is located and the connections between theterminals of the resistor and the external conductors are mounted onthis block. Thus the resistor and its connections are protected frommoisture and the unit may be readily inserted or removed from the liquidcontainer.

In detail, A is the resistor, which is preferably wound upon a flat coreB, having notched edges and formed of mica or other suitable insulatingmaterial. C' are terminals formed of strips of sheet-metal, which aremechanically connected to the core B by threading through a slit thereinand bending to form a loop, as shown in Fig. 5. The end of the resistoris preferably passed through an aperture in the terminal strip and thensecured by a rivet D, which also serves to clamp the two plies of thestrip to each other. E is a metallic housing or armor,

sulated resistor element may be inserted;

through the open end, leaving the terminals C projecting upward in therecess. After insertion of the insulated resistor the tube E isflattened under pressure-so as to force.

the walls thereof into clamping engagement with the insulated resistorand to also form good heat conducting contact. I is an insulator blockinserted in the recess H, said block being slotted transversely on itsinner face, as indicated at J, to form a clearance for the projectingportion of the core B and overlying insulator strips. The terminals Cpass through slits K in the block I and are then bent over and securedto connector plates L located in recesses M in the outer face of theblock. b The external conductors N are also attached to the connectors Land thus the electric circuit is completed.

The plug G is preferably provided with a threaded portion 0 which isadapted to engage a correspondingly threaded aperture in the wall of thecontainer P. Outside of this threaded portion is a seat portion Q whichmay be engaged with a suitable gasket R to form a liquid-tight seal. Theprojecting portion of the plug is preferably poly onal for conveniencein engaging a wrenc or other-tool for screwing it into the casing.

The construction described is one particularly adapted for commercialmanufacture, inasmuch as the electrical unit and the armor therefor maybe separately constructed. Thus the tube E may be flattened, closed atits lower end and welded at its outer end to the threaded plug G. Theelectrical unit comprising the core B,.resistor A and outer insulatorstrips S may then be inserted through the open outer end of the tube Eand secured by the compression of the tube, as before described. Theblock I may then be inserted, the terminals C being threaded through theslits in said block and then bent down and secured to the connectorplates L in the recesses M. Thus the work of assembly requires littleskill. and no electrical knowledge, while the work of forming the armorand plug is purely mechanical;

The joint between the tube E and plug is preferably welded and byflowing in molten metal a fillet is formed at each side, increasing thestrength and insuring a perfect water seal. 7

That we claim as our invention is: v

' 1. An electrical heating unit, comprising a flattened tube closed atone end, a plug or cap secured to the opposite end and recessed to be inopen communication with the interior or" the tube an insulated resistorinserted in the flattened tube, said insulated resistor and flattenedtube being in good heat conductin engagement, a terminal on saidresistor projecting into the recess in the plug, an insulator black insaid recess slitted for the passage of said terminal therethrough, andmeans for connecting said terminal to external conductors mount-- edonsaid insulator block.

2. An electrical heatin unit, comprising a flattened seamless tubeclosed at one end, a threaded plug integrated with the oppo-' site endof said tube said plug having a recess in open communication with the interior of the tube, an insulated resistor inserted 111 said tube andpro]ect1ng into said recess, an insulator block in said recess slo 7 andmeans for connecting said terminal with the external conductor mountedon said block.

3. An electrical heating unit, comprising a flattened tube closed at oneend, a plug or cap integrated with the opposite end and provided with arecess into4 open communication with the interior of the tube, a fiatinsulator core, a resistor mounted on said core, a terminal in the formof a loop pass ing through a slit in the insulator core to form amechanical connection therewith, said terminal being electricallyconnected with the resistor, ail-insulator block in said recess slittedfor the passage of the terminal therethrough, the projecting portion ofsaid terminal being bent over said block to retain the same, andmeans-mounted on said block for connecting said terminal to: theexternal conductor.

In testimony whereof-we affix our signatu'res.

' FRANK KUHN.

JAY A. HAND.

